1d73bec4c1
Document EIO from msync(2). Inspired by PR: docs/165929 [1] Reviewed by: jilles MFC after: 2 weeks
125 lines
3.4 KiB
Groff
125 lines
3.4 KiB
Groff
.\" Copyright (c) 1991, 1993
|
|
.\" The Regents of the University of California. All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 4. Neither the name of the University nor the names of its contributors
|
|
.\" may be used to endorse or promote products derived from this software
|
|
.\" without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" @(#)msync.2 8.2 (Berkeley) 6/21/94
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd March 18, 2012
|
|
.Dt MSYNC 2
|
|
.Os
|
|
.Sh NAME
|
|
.Nm msync
|
|
.Nd synchronize a mapped region
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.In sys/mman.h
|
|
.Ft int
|
|
.Fn msync "void *addr" "size_t len" "int flags"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn msync
|
|
system call
|
|
writes any modified pages back to the file system and updates
|
|
the file modification time.
|
|
If
|
|
.Fa len
|
|
is 0, all modified pages within the region containing
|
|
.Fa addr
|
|
will be flushed;
|
|
if
|
|
.Fa len
|
|
is non-zero, only those pages containing
|
|
.Fa addr
|
|
and
|
|
.Fa len-1
|
|
succeeding locations will be examined.
|
|
The
|
|
.Fa flags
|
|
argument may be specified as follows:
|
|
.Pp
|
|
.Bl -tag -width ".Dv MS_INVALIDATE" -compact
|
|
.It Dv MS_ASYNC
|
|
Return immediately
|
|
.It Dv MS_SYNC
|
|
Perform synchronous writes
|
|
.It Dv MS_INVALIDATE
|
|
Invalidate all cached data
|
|
.El
|
|
.Sh RETURN VALUES
|
|
.Rv -std msync
|
|
.Sh ERRORS
|
|
The
|
|
.Fn msync
|
|
system call
|
|
will fail if:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EBUSY
|
|
Some or all of the pages in the specified region are locked and
|
|
.Dv MS_INVALIDATE
|
|
is specified.
|
|
.It Bq Er EINVAL
|
|
The
|
|
.Fa addr
|
|
argument
|
|
is not a multiple of the hardware page size.
|
|
.It Bq Er EINVAL
|
|
The
|
|
.Fa len
|
|
argument
|
|
is too large or negative.
|
|
.It Bq Er EINVAL
|
|
The
|
|
.Fa flags
|
|
argument
|
|
was both MS_ASYNC and MS_INVALIDATE.
|
|
Only one of these flags is allowed.
|
|
.It Bq Er EIO
|
|
An error occurred while writing at least one of the pages in
|
|
the specified region.
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr madvise 2 ,
|
|
.Xr mincore 2 ,
|
|
.Xr mlock 2 ,
|
|
.Xr mprotect 2 ,
|
|
.Xr munmap 2
|
|
.Sh HISTORY
|
|
The
|
|
.Fn msync
|
|
system call first appeared in
|
|
.Bx 4.4 .
|
|
.Sh BUGS
|
|
The
|
|
.Fn msync
|
|
system call is usually not needed since
|
|
.Bx
|
|
implements a coherent file system buffer cache.
|
|
However, it may be used to associate dirty VM pages with file system
|
|
buffers and thus cause them to be flushed to physical media sooner
|
|
rather than later.
|